Fuse mounting



S. l. LINDELL FUSE MOUNTING Oct. 18, 1949.

2 Sheets-$heet 1 Filed April 22, 1946 1N6 ULAT f0.

IE "I Invenor: JggrdJZndeZZ Brmu WM, m

FUSE MOUNTING Filed April 22, 1946 2 Sheets-Sheet 2 PatentedOct. is, me

UNITED STATES PATENT OFFICE FUSE MOUNTING fligardllmcbicagetlllealdgnertcfltc Electric Cenpan'y,ac0rp0ratlonofbelawue Application April :2, 1m, Serial No. coasts :1 Claims. (01. zoo-414) This invention relates, generally, to electric circuit interrupter mounting devices and it has particular relation to mounting devices for high voltage fuses in regard to detachably connecting the same into a circuit. It may be said also that it relates to fuse clips for detachably mounting high voltage fuses in an electric circuit and for providing the required electrical connection between a fuse tube terminal and its associated line terminal.

The present invention is particularly adapted for use with the fuse construction disclosed in the copending application of Sigurd I. Lindell and Charles H. Baker, Serial No. 663,832, filed April 22, 1946. Also, it is specifically designed for use with the drop out fuse construction disclosed in the copending application of Sigurd I. Lindell, Serial No. 663,834, filed April 22, 1946.

The fuse construction of Lindell and Baker is intended for use on electric power systems operating at 115 kv. and at a frequency of 60 cycles. The fuse tube in assembled condition for mounting on the line terminals and connection thereto has a weight of the order of 40 to 50 pounds. The fuse tube itself is over 4 feet long and has an external diameter of about 3 inches. The end terminals are constructed in corresponding proportions. As set forth in detail in the copending application of Lindell, provision is made for moving or dropping out the fuse tube to the open circuit position where an air gap is introduced in the circuit so that the fuse tube, after the fuse has blown, will not be required to withstand the system voltage. Since the fuse is designated for out-of-doors mounting, provision must be made for disengaging its terminals from the line terminals in a positive manner regardless of the presence of sleet, corrosion etc. Accordingly, it is required that particular attention be paid to the arrangement and construction of the fuse clips and the manner in which the same are engaged by the fuse tube terminals.

It is, therefore, an object of this invention to provide contact clips and a fuse tube terminal construction for operation therewith that will be simple and efficient in operation, which may be readily and economically manufactured and which will permit the fuse tube to be placed in service readily and which will facilitate moving and effect positive movement of the fuse tube to the drop out position when the fuse blows.

Another object is to introduce a readily disengageable rigid connector between each fuse tube terminal and its associated contact clip for z providing direct electrical connection therebctween.

A further object is to provide a contact link having wiping contact engagement not only with the contact surface of the contact clip but also with the contact surface of the fuse tube terminal associated therewith on closing and relative rocking or rolling movement on disengagement without relative sliding.

Another object is to arrange the mechanical connection between the fuse tube terminal and the associated contact clip which provides the electrical connection therebetween so as to bias the fuse tube away from the closed position thereof. 4 A still further object is to employ contact links for interconnecting the fuse tube terminal and the associated contact clips and to arrange the same "so that a rocking movement takes place between each end of each link and the contact surface engaged thereby.

A further object is to provide for guiding the contact links into the associated fuse clip when the fuse is moved toward the closed position and to limit the movement thereof relative to the associated fuse tube terminal before the contact engagement takes place.

Still another object of this invention is to avoid the use of flexible shunts for interconnecting the galrtiltact links with the associated fuse tube ter- Another object is to employ a toggle action to provide high pressure line contact engagement with the clip and associated fuse tube terminal with the major component of the force of the toggle acting at right angles to the direction of movement of the fuse tube to the open position whereby the holding force required to be exerted by the latch in holding the fuse tube in the closed position is reduced.

Other objects of this invention will, in part, be obvious and in part appear hereinafter.

This invention is disclosed in the embodiment thereof shown in the accompanying drawings and it comprises the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereinafter set forth and the scope of the application of which will be indicated in the appended claims.

For a more complete understanding of the nature and scope of this invention, reference can be had to the following detailed description, taken in connection with the accompanyingdrawings, in which;

amass Figure 1 is a view, in side elevation, of a drop out fuse tube mounted onan insulator stack and provided with the fuse mounting of the present invention;

Figure 2 is a view, in side elevation and at an enlarged scale, of the upper latch terminal construction shown in Figure 1;

Figure 3 is a top plan view of the upper contact clip and the upper fusetube terminal as the fuse tube is moved toward the closed position; I

Figure 4 is a view, similar to Figure 3, but showing the fuse tube in the closed and latched position, certain parts being broken away in order to more clearly illustrate the details of construction; and

Figure 5 is a fragmentary perspective view, at an enlarged scale, showing the manner in which a contact link is arranged to have direct contact engagement with the associated fuse tube terminal.

Referring now particularly to Figure 1 of the drawings, it will be observed that the reference character It designates, generally, a fuse construction such as disclosed in the copending application of Lindell and Baker referred to hereinbefore. The fuse construction It includes a tube i l of suitable insulating material having terminals or ferrules l2 and I! at its ends for contact engagement with fuse contact clips, shown generally at It and 15, respectively. The contact clips 14 and I5 are carried by contact clip supports or power line terminals which are shown generally at l6 and l1.

The terminals i6 and II are arranged to be mounted in insulated spaced relation. The amount of insulation will, of course, depend upon the voltage impressed therebetween. The line terminals l6 and I! may be variously mounted. They may be mounted horizontally, or at an angle, or they may be mounted one above the other as shown in Figure 1. v

In the particular construction shown in Figure 1 the power line terminal i6 is carried by a support pipe I8 that, in turn, is carried by a stack of insulators l9. Midway of the stack of insulators l9 there is provided a mounting bracket 2| for carrying the lower power line terminal l1. Conductors 22 and 23 may be connected, as illustrated, to the power line terminals [6 and I1 and serve to connect the fuse construction ill into the circuit.

The fuse construction I0 is of the drop out type. The details of construction of the drop out mechanism are more fully set forth in the copending application of Lindell, above referred to. It is here pointed out that the upper fuse tube terminal I! has associated therewith a latch mechanism, which is indicated, generally, at 2. This serves to hold the fuse construction ill in the position shown in the drawing until the fuse blows. When the fuse blows, a latch tube 25 is moved upwardly to operate the latch mechanism 24 so as to permit the fuse construction It to automatically fall under the influence of gravity to the position shown by the broken lines in Figure l assisted by the forces exerted by the fuse contact clips l4 and I! as will appear hereinafter.

The lower line terminal or contact clip support H has a hinge extension 21 which extends forwardly of the terminal I! and is slotted, as indicated at 28, for receiving trunnions 29, only one of which is shown. The trunnions 29 are integrally formed with and constitute extensions of a trunnion and pivot contact assembly or cradle the upper power line terminal II. A coil spring ll surrounding the bolt I2 serves to bias the latch lever 82 in a clockwise direction. At its forward end the latch lever 22 carries a hook roller ll behind which a latch roller 38 is arranged to be positioned to hold the fuse construction I I in the closed position. The latch roller II is carried by a nose portion I! that is formed integrally with an upper fuse tube holder that is indicated, generally, at It. The upper fuse tube holder 2. surrounds the upper end of the upper fuse tube terminal i2 and is held in place thereon by a retaining screw 3!. The nose portion 31 has an inclined face 40 which, when the fuse construction II is moved toward the closed position, first engages the roller 35 and lifts the same together with the latch lever 22 sufficiently to permit the latch roller it to pass thereunder to the latched position shown in Figure 2. A stop pin 4|, threaded into. the upper line terminal I! through the bottom of the contact clip H, serves to limit the inward movement of the fuse construction II, the head of the retaining screw 29 on engaging the outer end of the stop pin 4i preventing further inward movement of the fuse construction it.

With a view to releasing the latch roller 26 from behind the hook roller 35, a pry out lever 43 is mounted for rocking movement about the axis of the roller 15 on the latch lever 22. Its movement relative thereto in a clockwise direction is limited by a web 42' extending therefrom and arranged to engage the forward end of the latch lever 32. The pry out lever ll is biased for movement in a clockwise direction by a leaf spring 44 that extends from the upper surface of the latch lever 32 near its rear end and bears against the under side of the pry out lever 42, as illustrated. A reenforcing spring 44', which is relatively stiff as compared to the leaf spring N, is arranged to cooperate with the adjacent end of the pry out lever 43 to aid in lifting the hook roller 35 above the latch roller 16.

In order to move the pry out lever II in a counterclockwise direction so as to raise the latch lever 32 and move the hook roller 35 out of engagement with the latch roller IS, the pry out lever 43 has bosses 45 extending oppositely therefrom on opposite sides of the latch tube 25, only one of the bosses 45 being shown in the drawing. Fingers 48, extending from a pull ring and trip member, indicated generally at 41, are arranged to engage the underside of the bosses 45 and to move the same upwardly. The member I1 is rockably mounted by a pin it which extends through ears 4! integrally formed with the upper fuse tube holder SI. The member 41 also includes an integrally formed ring for receiving 'the hook of a switch stick to permit manual operation of the member 41 and tripping of the latch mechanism 24. A coil spring 5|, surrounding the pin ll, serves to normally bias the member 41 for movement in a counter-clockwise direction.

When it is desired to manually trip the latch mechanism 24, the hook of a switch stick is inserted in the ring SI and member 41 is rocked a inacloekwisedirectionagainsttheforceofthe spring 'ito lift the fingers I and thereby liftthe bosses II extending from the pry' out lever 43. As previously described, this rocks the pry out lever 4! until the leaf spring it engages the reenforcing spring "whereupon the latch lever 32 is lifted and the hook roller 3' is moved out of engagement with the latch roller ii. The

fuse construction II is then free to fall to the position shown by the broken lines in Figure l.

The latch mechanism It may be tripped, also, when the fuse construction It blows. As set forth in more detail in the copending application of Lindell, above referred to, when the fuse construction it blows, the latch tube ll moves upwardly through a slight distance. Advantage istaken of this movement to trip the latch mechanism it. For this purpose the latch tube 2' carries a flange 52 which, when moved upwardly, engages downwardly extending nose portions It, only one of which is illustrated, from the pry out lever 43. Thus, the pry out lever 48 is operated by movement of the latch tube 25 upwardly in the same manner that it is operated by rocking of the member 41 manually by a switch stick.

The contact clips H and it, which serve to connect the fuse tube terminals l2 and It to the power line terminals i6 and H, are of duplicate construction. The manner in which each of the terminals i2 and I1 is connected to its contact a a clip is also essentially the same for each. Ac-

arms of the contact spring ii are provided with apertures 62 for receiving projections 63' of guide pins 63 which extend from the contact shoes 58. as illustrated. The combination of the copper contact connector 51 and the contact spring 6i provides for good electrical conductivity for the clip I l and at the same time the required degree of resiliency to urge the contact surfaces 60 of for wiping contact engagement with the contact surfaces It ofthecontactshoesllasthefuse consfl-uction llismovedtowardtheclosedposition fromthatshowninl'igurestothatshown inl'igureeandtoprovideforrollingorrocking movement in the reverse direction to overcome any tendency to stickin the presence of corrosion, sleet, etc. and to facilitate breaking loose therefrom. The rounded inner ends ll of the linkstlalsohaveasimilarcontactt with the adjacent surface I2, Figure 5, of the the contact shoes 58 toward each other with the required pressure, sufficient not only to assure the necessary contact pressure but also, as will hereinafter appear, to bias the fuse construction Ill outwardly away from the closed position thereof. The contact clip it may be held in place on the power line terminal It by suitable cap bolts 64 which extend through the base portion of each of the spring contacts 51 and the contact spring 6i.

It is desired that a direct electrical connection be provided between the contact-shoes 58 and the outer surface of the fuse tube terminal l2. One reason for this is to avoid the necessity of using a flexible shunt to complete the connection. For this purpose, as illustrated in Figures 3 and 4 of the drawings, pivot contacts or contact links 61 of suitable conducting material, such as brass, are

pivoted on pins 68 which extend through'clearance holes 69, Figure '5, in the links 61 and support them between ears 1n integrally formed with and extending radially outwardly from the upper fuse tube holder 38. The ends of thelinks Bl are rounded as indicated at H so as to provide terminal II. This is permittedbecause the links ll are relatively loosely carried by the pins II as provided by the clearance holes I.

It will now be obvious that, when the fuse construction II is in the closed position, as illustrated in Figure 4 of the drawings, the Jaws of the contact clip it will be spread apart and the contact spring II will exert a relatively great pressure through the guide pins 03 and contact surfaces ll of the contact shoes ll onto the links 01 and they in turn will transmit this pressure directly against the surface I2 of the terminal l2. Since the links 61 pivot slightly about the pins 68 when the fuse construction is moved to the closed posibetween the surfaces ii of the links 81 and the cooperating contact surfaces 80 of the contact shoes 58 as the fuse construction It is moved to the closed position and the rolling action between these surfaces when the fuse construction It is moved away from the closed position, it is pointed out that these two different and desirable actions are the result of different interactions between the movement of the contact shoes 58 and the fuse construction it during the closing and opening movements of the latter. Considering first the closing movement, after the surface 'li engages the surface til, the vertical axis of the surface H, which is a cylindrical surface, cannot move further inwardly because of the inner ends of the contact shoes 58 which extend toward each other and act as stop means but rather this vertical axis shifts sideways to spread the contact shoes it apart asthe fuse construction It is moved to the latched position, the stress being transmitted through the links 61 in compression. In so doing there is a wiping or sliding action between the surfaces Ii and 60. Now,

when the fuse construction it is unlatched, it

moves outwardly and bodily carries with it the links 61. At the same time the contact shoes 58 move inwardly but, because the links 61 are being moved bodily away from the closed position at the same time and the vertical axis of the cylindrical surface II is moved outwardly, the surfaces H and ill roll or rock with respect'to each other rather than have a relative wiping or sliding action as is the caseduring the closing operation of the fuse construction it. A similar action -connector 51 is about 9 a,ses,sso

7 provided by the hole 69, through which the pin OI extends, when the fuse construction I! is swung out of its closed position, the surface 1] rocks over the surface 12.

It will be observed that the links 61 when pivotally mounted, as described, on the upper fuse tube. holder 38 cooperate therewith in the manner of a toggle. The resilient force of the contact spring 61 is exerted through the links 61. However, the construction is such that the fuse in the closed position does not move the links 61 past the center position of the toggle; rather they are always maintained on the release side of this position. Consequently, the contact spring 6| always functions to urge the fuse construction l away from the closed position. It is held in this position only by the latch mechanism 24, previously described.

With a view to guiding the links 61 into operative position between the contact shoes 58 pivot contact springs 13 are secured, as by screws 14, to the upper fuse tube holder 38. The outer curved ends 15 of the springs 13 bear against the links 81 and normally urge them toward the positions thereof shown in Figure 3 of the drawings against webs 38' integrally formed with the upper fuse tube holder 38. Stop pins 16 are located in the 1inks 61 to cooperate with webs 11, which also are integrally formed with the upper fuse tube holder 38, for limiting the movement of the links 61 away from the fuse tube In when they are out of engagement with the contact shoes 58 and a force should be applied to the links 61 suihcient to overcome the springs 13.

It has been indicated hereinbefore that the fuse construction l0 disclosed herein is particularly designed for operation in a power circuit which is energized at 115 kv. It will be understood that this voltage rating is set forth herein merely for illustrative purposes and that the principles of construction disclosed herein can be used for fuses that are adapted to function in a system operating at other voltages. By way of further illustration it is pointed out that the contact connector 51 and the contact spring 6| have a width of about 1%" and that the outer span thereof between the outer ends of the contact The contact spring 6| urges the contact shoes 58 toward each other with a force of the order of about 150 pounds. However, because of the arrangement of the links 61, only a small component of this force is applied to the latch 24. The links 61 are preferably silver plated and they may have a, width of 19;" and a length of 2%". They.may be thick. It is repeated that these data are set forth merely to provide an indication of the relative sizes of the parts involved and are not to be considered as limiting the scope of the invention.

Since the contact shoes 58 are carried at the outer ends of the arms of the U-shaped contact connector 51, they have a relatively great freedom of movement and thus are essentially self aligning with respect to the links 61. Substantially line contact therewith is provided. This is highly desirable because the normal current carrying capacity of the fuse may be of the order of 200 to 300 amperes. This self aligning feature is promoted by the connection of the contact spring 6| thereto through the round headed guide pins 63, substantially point contact engagement therebetween being had.

Since certain further changes can be made in the foregoing construction and different embodimerits of the invention can be made without departing from the spirit and scope thereof, it is intended that all matter shown in the accom- Denying drawings and described hereinbefore shall be interpreted as illustrative and not in a limiting sense.

What is claimed as new is:

1. separable contact means for interconnecting a fuse tube terminal and a power line terminal comprising, in combination, means providing a pair of opposed contact surfaces, support means carried by said fuse tube terminal on opposite sides thereof, and a pair of contact links carried by said support means for engaging said contact surfaces and said opposite sides of said fuse tube terminal to provide direct electrical connection therebetween.

2. separable contact means for interconnecting a fuse tube terminal and a power line terminal comprising, in combination, means providing a pair of opposed contact surfaces, support means carried by said fuse tube terminal on opposite sides thereof, and a pair of contact links carried by said support means for engaging said contact surfaces and said opposite sides of said fuse tube terminal to provide direct electrical connection therebetween, the contact making ends of said links being rounded to provide relative rocking movement between them and the associated contact surfaces of said means and said fuse tube terminal when the fuse tube is moved to the open position.

3. separable contact means for interconnecting a fuse tube terminal and a power line terminal comprising, in combination, means providing a pair of opposed contact surfaces, support means carried by said fuse tube terminal on opposite sides thereof, and a pair of contact links loosely pivoted on said support meets to engage intimately the adjacent portions of the surface of said fuse tube terminal when the fuse tube is moved to the closed position and said links engage said contact surfaces of said contact clip.

4. separable contact means for interconnecting a fuse tube terminal and a power line terminal comprising, in combination, means providing a pair of outwardly flared resiliently mounted contact surfaces, a pair of contact links for engaging said contact surfaces and spreading the same apart when the fuse tube is moved to the closed position, and means for mounting said contact links on opposite sides of said fuse tube terminal 50 as to engage the surface thereof with a pressure determined by the force exerted by said resiliently mounted contact surfaces when the fuse tube is in the closed position.

5. Separable contact meam for interconnecting a fuse tube terminal and a power line terminal comprising, in combination, means providing a pair of outwardly flared resiliently mounted contact surfaces, a pair of contact links for engaging said contact surfaces and spreading the same apart when the fuse tube is moved to the closed position, means for mounting said contact links on opposite sides of said fuse tube terminal so as to engage the surface thereof with a pressure determined by the force exerted by said resiliently mounted contact surfaces when the fuse tube is in the closed position, and spring means for guiding said contact links into engagement with said contact surfaces and for limiting the movement thereof relative to said mounting means when they are out of engagement therewith.

8. separable contact means for interconnect ingafusctubetermlnalandapowerlineterminal comprising. in combination, means providing a pair of outwardly flared resiliently mounted contact surfaces, a pair b1 contact links for engaging said contact surfaces and spreading the same apart when the fuse tube is moved to the closed position, and means for mounting said contact links on opposite sides of said fuse tube terminal so as to engage the surface thereof with a pressure determined by the force exerted by said resiliently mounted contact surfaces when the fuse tube is in'the closed position. the relationship between said outwardly flared contact means and said contact links when the fuse tube occupies the closed position being such that the fuse tube is biased to the open position.

7. Separable contact means for interconnecting the terminals of a fuse tube and the corresponding power line terminals comprising, in combination, a pair of generally U-shaped contact clips each having a pair of outwardly flared resiliently mounted contact surfaces, and a pair of contact links mounted pivotally on opposite sides of each fuse tube terminal and to engage the contact surfaces of the corresponding contact clip.

8. separable contact means for interconnecting the terminals of a fuse tube and the corresponding power line terminals comprising, in combination, a pair of generally U-shaped contact clips each having a, pair of outwardly flared resiliently mounted contact surfaces, support means carried by each fuse tube terminal on opposlte sides thereof, and a pair of contact links carried by each support means for engaging the contact surfaces of the corresponding contact clip and said opposite sides of the fuse tube terminal associated therewith to provide direct electrical connection therebetween.

9. separable contact means for interconnecting the terminals of a fuse tube and the corresponding power line terminals comprising, in

tact making ends of said links being rounded to provide relative wiping movement between them and their associated contact surfaces when the fuse tube is moved to the closed position.

10. separable contact means for interconnecting the terminals of a fuse tube and the corresponding power line terminals comprising, in combination, a pair of generally U-shaped contact clips each having a pair of outwardly flared resiliently mounted contact surfaces, a pair of contact links for engaging the contact surfaces of each contact clip and spreading the same apart when the fuse tube is moved to the closed position, and means for mounting each pair of contact links on opposite sides of each fuse tube terminal so as to engage the surface thereof with a pressure determined by the force exerted by the associated resiliently mounted contact surfaces when the fuse tube is in the closed position.

11. separable contact means for interconnecting the terminals of a fuse tube and the corresponding power line' terminals comprising, in combination, a pair of generally U-shaped contact clips each having a pair of outwardly flared amass resiliently mounted contact surfaces, a pair of contact links for engaging the contact surfaces of each contact clip and spreading the same apart when the fuse tubeis moved to the closed position, and means for mounting each pair of contact links on opposite'sides of each fuse tube terminal so as to engage the surface thereof with a pressure determined by the force exerted by the associated resiliently mounted contact surfaces when the fuse tube is in the closed position, the relationship between the outwardly .flared contact surface portions of each contact clip and the associated pair of contact links when the fuse tube occupies the closed position being such that the fuse tube is biased to the open position.

12. separable contact means for interconnecting a fuse tube terminal and a power line terminal comprising, in combination, means on said power line terminal providing a pair of outwardly flared resiliently mounted contact surfaces, and a pair of toggle links carried by said fuse tube terminal on opposite sides thereof for engaging. said contact surfaces with a toggle action.

13. The invention, as set forth in claim 12, wherein the toggle links in the closed position are on the release side of the toggle.

14. The invention, as set forth in claim 12,

wherein .the ends of the links engaging the con-v contact connector whereby self-aligning substantially line contact'engagement is had with the toggle links, and a generally U-shaped contact spring is nested with said contact connector and the ends thereof urge said contact shoes into engagement with said links, there being relatively small area contact engagement between said contact shoes and said ends of said contact spring.

16. A separable contact construction comprising, in combination, a contact member having a convex contact surface, a contact arm biased toward said contact surf-ace, said contact member and said arm being movable relative to each other, contact means for interconnecting said arm and said contact member, said contact means having a convex contact surface for engaging said convex contact surface of said contact member, and stop means on said contact member cooperating with said contact means whereby said contact surfaces engage with a wiping action and disengage with a rolling or rocking action on relative movement of said contact member and arm toward and away from each other.

17. A separable contact construction comprising, in combination, .a contact member having oppositely facing convex contact surfaces, 9. pair of arms on opposite sides of and biased toward said contact surfaces, said contact member and said arms being movable relative to each other, contact means for interconnecting said arms and said contact member, said contact means'havin convex contact surfaces for engaging said convex contact surfaces of said contact member, and stop means on said contact member cooperating with said contact means whereby the mutually engaging contact surfaces engage with a wiping action and disengage with a rolling or rocking action on relative movement of said contact amass 11 memberandarmstowardandawayfromeach other.

18. A separable contact construction for interconnecting a line terminal and a movable termi-.

'nal at one end of an elonagtc member that is pivoted at the other end comprising, in combinatlon, a contact member carried by said movable terminal having oppositely facing convex contact surfaces extending parallel to the iongitudinal axis of said elongate member, a pair of arms carried by said line terminal on opposite sides of and biased toward said contact surfaces, contact means for interconnecting said arms and said contact member, said contact means having convex contact surfaces parallel to said longitudinal axis when said elongate member is in the circuit closed position forengaging said convex contact surfaces of said contact member, and stop means carried by said:

movable terminal and cooperating with said contact means whereby the mutually engaging contact surfaces engage with a wiping action and disengage with a rolling or rocking action on movement of said elongate member into and out of the circuit closed position.

19. In a dropout fuse construction, in combination, a pair of stationary line terminals in insulated spaced relation, contact means on each line terminal providing a pair of opposed contact surfaces, a fuse tube, terminals at the ends of said fuse tube, support means carried by each fuse tube terminal on opposite sides thereof, a pair of contact links carried by each of said support means for engaging the corresponding pair 12 ofopposedeontaetsurfacesandthe opposite sidesoftheassociatedfmetubeterminalto provide direct electrical connection therebetween, means pivotally mounting said fuse tube nearoneendwherebythesamecanbemoved totheclosedpoaitionandcanfallunderthe iniluenceofgravitytotheopenposition,andreleasable latch means mounted near the other endofaaidfusetubeforholdingthesamein theclosedpositionwithsaidcontactlinksinen- Basement with said contact surfaces and the onilposite sides of the associated fuse tube termi- 20. The-invention, as set forth in claim 19, wherein the contact means comprises a generally U-shaped contact clip and the contact surfaces are provided by outwardly flared resiliently mounted contact enga ing p rtions thereon.

21. The invention, as set forth in claim 19, wherein thecontact means comprises a generally U-shaped contact clip having resilient arms biased each other for engagement by the contact links indivdual thereto and acting to urge the fuse tube away from its closed position through said contact links.

, BIGURD I. LiNDlillL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATE PATENTS Name 

